There are currently services that allocate hardware resources of computers installed at a hub, such as a data center, to users and allow them to use the hardware resources. Such a service may be implemented using cloud computing technology, and is sometimes referred to as Infrastructure as a Service (IaaS). The hardware resources allocated to users may include storage areas of memory apparatuses, such as hard disk devices. For example, when creating a virtual machine for a user, a computer selects a storage area from pooled, unallocated storage areas and allows the virtual machine to use the selected storage area. When, for example, deleting the virtual machine created for the user, the computer releases the storage area of the virtual machine and adds it back to the pooled storage areas.
The above-described method for dynamically allocating a storage area may reallocate a storage area used by a user in the past to a different user. In this regard, it is preferable to initialize (format) the storage area to be reallocated in terms of security so that information of the previous user is not passed onto the next user. The computer initializes the storage area, for example, by writing a predetermined bit sequence to the storage area. The initialization of the storage area is preferably completed before the storage area becomes accessible due to the reallocation.
Note however that because the initialization process sometimes takes much time, it may be considered desirable to allow a storage area whose initialization has not been completed to be allocated to a user so as not to keep the user waiting in the stage of hardware resource allocation whilst proceeding with the initialization in the background. If, when access to a storage area is requested by the user, the initialization of the storage area has yet to be completed, the coordination between the data access and the initialization process needs to be adjusted.
For example, a storage control apparatus has been proposed which determines, in response to an access request from a host, whether an area on a disk to which access is requested has already been formatted, and then logically formats the area before the disk access if the area has not yet been formatted. In addition, a recording and reproducing apparatus has been proposed in which, in response to a data recording request from a host computer after background formatting of a storage medium is started, the background formatting is interrupted to allow data to be recorded on the storage medium. Further, a storage system has been proposed in which, in response to a read request designating an uninitialized area, predetermined null data is returned, and in response to a write request designating an uninitialized area, write access is caused to wait until initialization of the designated area is completed.
Japanese Laid-open Patent Publication No. 2003-29934
Japanese Laid-open Patent Publication No. 2003-45117
Japanese Laid-open Patent Publication No. 2005-11317
However, there is room for improvement in the conventional technologies described above in terms of the coordination between the data access and the initialization process. For example, the method for simply interrupting the initialization process to thereby write data to a designated storage area in response to a write request fragments a storage area to be initialized, which possibly results in cumbersome and inefficient control of the initialization process.